• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.191-193
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• 2010

In this study, compared with national control point offering in NGII executing Network-Based RTK measurement. As a result, can utilize in various field such as Geodetic Survey/GIS, ITS, Car Navigation, Mobile because error of actuality coordinate and about 0.5m publishes.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.11 no.1
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• pp.37-45
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• 1993

We research on the coordinate transformation between Korean geodetic system and WGS 1984. We made the wide area an object of our research. This area covers the range of longitude $1^\circ$ 32'and latitude $1^\circ$ 7'and is four times wider than a first stage research published in 1992. For this research, we performed GPS observations at 10 control point (seven astrogeodetic points, three triangulation points) and eight banch marks nearby control points, and then transformed the coordinates of WGS 84 to Korean geodetic system using the 7 parameter method, Molodensky method and MRE method. From this test, we compared the precision of the coordinate transformation by each method and checked which method is more applicable to Korea. We could find that the precision by 7 parameter method is three times better than the other methods and that the coordinate transformation by 7 parameter method is possible with the precision of 0".017, 0".016, 0.329 m in latitude, longitude and height. We could check and correct the height blunder of the control points by the bench marks nearby control point. We also could find the precision of coordinate transformation is more improved by the correction of height blunder.t blunder.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.15 no.2
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• pp.195-206
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• 1997

By this time, in order to measure baseline in a few minutes, we must have used expensive dual frequency receiver. Recently, low-priced single frequency receiver have taken place of dual frequency receiver at short base-line by advancement in software development, improvements in geodetic survey receiver system. In this study, according to the observation time and measurement interval, we analyzed differences of each components of baseline by field experiment and we propose the criterion for the minor control point surveying by single frequency GPS receiver.

• Journal of Astronomy and Space Sciences
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• v.30 no.4
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• pp.269-277
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• 2013

In this study, we present results of precise orbital geodetic parameter estimation using satellite laser ranging (SLR) observations for the International Laser Ranging Service (ILRS) associate analysis center (AAC). Using normal point observations of LAGEOS-1, LAGEOS-2, ETALON-1, and ETALON-2 in SLR consolidated laser ranging data format, the NASA/GSFC GEODYN II and SOLVE software programs were utilized for precise orbit determination (POD) and finding solutions of a terrestrial reference frame (TRF) and Earth orientation parameters (EOPs). For POD, a weekly-based orbit determination strategy was employed to process SLR observations taken from 20 weeks in 2013. For solutions of TRF and EOPs, loosely constrained scheme was used to integrate POD results of four geodetic SLR satellites. The coordinates of 11 ILRS core sites were determined and daily polar motion and polar motion rates were estimated. The root mean square (RMS) value of post-fit residuals was used for orbit quality assessment, and both the stability of TRF and the precision of EOPs by external comparison were analyzed for verification of our solutions. Results of post-fit residuals show that the RMS of the orbits of LAGEOS-1 and LAGEOS-2 are 1.20 and 1.12 cm, and those of ETALON-1 and ETALON-2 are 1.02 and 1.11 cm, respectively. The stability analysis of TRF shows that the mean value of 3D stability of the coordinates of 11 ILRS core sites is 7.0 mm. An external comparison, with respect to International Earth rotation and Reference systems Service (IERS) 08 C04 results, shows that standard deviations of polar motion $X_P$ and $Y_P$ are 0.754 milliarcseconds (mas) and 0.576 mas, respectively. Our results of precise orbital and geodetic parameter estimation are reasonable and help advance research at ILRS AAC.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.2
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• pp.265-274
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• 2014

A recent air defense missile system(ADMS) is required to have a capability to intercept super-high speed targets such as tactical ballistic missiles(TBMs) by performing engagement control efficiently. The air defense missile system should be ready to engage the TBMs as soon as the ADMS detects TBMs because falling velocity of TBM is very high and remaining time interval to engage TBM is very short. As a result, the ADMS has to predict the trajectories of TBMs accurately with estimated states of dynamics to generate predicted intercept point(PIP). In addition, it is needed to engage TBMs accurately via transmitting the obtained PIP data to the corresponding intercept missiles. In this paper, an analysis about the relationship between ballistic coefficient and PIP accuracy which is depending on geodetic height of the first detection of TBM is included and an issue about effective engagement control for the TBM is considered.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.5
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• pp.437-449
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• 2007

This paper deals with issues of GPS network adjustment for the purpose of determining the $3^{rd}$ order national geodetic control points based on the Korean Geodetic Datum which has newly adopted in the country since early 2003. After examining and arranging all the observations, GPS baseline analyses were performed to estimate baseline vectors between two control points. All the observations were divided into 17 block networks in order to accelerate the adjustment efficiency. After applying a minimally constrained adjustment technique to each of the block networks for the sake of detecting outliers and examining network precision, over constrained adjustments by fixing all of the $2^{nd}$ order control points within the block network were carried out to derive final coordinate sets. The final solutions indicated that the accuracy of the adjusted coordinates was better than 1cm and 2cm in the horizontal and vertical component, respectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.16 no.2
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• pp.337-343
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• 1998

In Korea, map coordinates has been confused in use since the map projection system has been complicated by using two different methods i.e., Gauss conformal double projection and Gauss-Kruger projection which are com-plicated in using through history. So, we have to understand the two projections' characteristics and differences. In this study, we would find out a fact that the maximum difference occurred in longitude and latitude is about 15cm at the Korean peninsular. This shift is accepted as proper in GIS and cartographic application but should be considered carefully in converting of the geodetic control point coordinates.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.5
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• pp.393-398
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• 2007

According to the Korean datum change to a world geodetic system, the EDM area should be readjusted to provide consistent product over the country. The data set for EDM area is extracted from the previous KTN1987 DB and checked for the moved markers in XY network adjustment which provides quality verification. Then, EDM data set for the seven areas are rebuilt for the adjustment. Since the data is still based on the old datum, the coordinates of the data are transformed by applying the coordinate transformation parameters. Here, the transformation parameters, which were determined for the conversion of 1:50,000 topographic maps by NGII, were used. For each EDM point, the geoidal height from EGM96 model is applied to obtain the ellipsoidal height based on the GRS80. The measured distance projected onto GRS80 is adjusted using BL network adjustment by fixing 2nd order or 3rd order GPS control points. The results from the readjustment show the minimum standard error of 1.37" and the maximum standard error of 2.13". Considering the measurement accuracy of EDM (1.6" corresponding to about 2cm) and GPS position for fixed points (2cm), this result is considered to be reasonable and it is good for the practical use.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.5
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• pp.445-458
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• 2012

The objective of GPS control surveying is ultimately to determine coordinate sets of control points within targeted accuracy through a series of observations and network adjustments. To this end, it is of equivalent importance for the accuracy of these coordinates to be realistically represented by using an appropriate method. The accuracy representation can be quantitively made by the variance-covariance matrices of the estimates, of which features are sensitive to the mathematical models used in the adjustment. This paper deals with impact of functional and stochastic modeling techniques into the accuracy representation of the GPS control surveying with a view of gaining background for its standardization. In order to achieve this goal, mathematical theory and procedure of the single-baseline based multi-session adjustment has been rigorously reviewed together with numerical analysis through processing real world data. Based on this study, it was possible to draw a conclusion that weighted-constrained adjustment with the empirical stochastic model was among the best scheme to more realistically describe both of the absolute and relative accuracies of the GPS surveying results.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.4
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• pp.231-244
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• 2015

The accuracy of reference point of VLBI antenna is mandatory to perform collocation of different space geodetic techniques. In this study, we evaluated the optimal methods for the 3D circle fitting to enhance the accuracy of the reference point of VLBI antenna. Two kinds of methodologies for the orthonormal coordinate system with translation of planar observation point and the unitary coordinate transforamation were suggested and their fitting accuracies were evaluated where the orthogonal distance was calculated by residual between observation point and fitting model and the recursive calculation was performed to improve the accuracy of 3D circle fitting. Finally, we found that the methodology for the unitary coordinate transformation is highly appropriate to determine the optimal equation for azimuth-axis and elevation-axis of VLBI antenna. Therefore, the reference point of VLBI antenna with high accuracy can be determined by the intersection of the above two axises (azimuth-axis and elevation-axis). This result is expected to be utilized for a variety of researches for connection between VLBI observation results and the national control point.